The invention generally relates antenna systems and, more particularly, the invention relates to a reconfigurable adaptive wideband antenna.
The detection, location, identification, and characterization of electromagnetic (EM) signals of types that have a low probability of intercept is an increasingly challenging problem. In general, EM signals with a low probability of intercept are transmitted by adversarial sources and thus employ various methods to reduce their signature. Such methods include frequency hopping, multiple signal polarizations, and spread-spectrum encoding techniques. In addition, the locations of the sources of such signals are not fixed and may change quite rapidly. The number of sources or EM signals that need to be located and tracked may also change depending on the particular circumstances.
A broadband antenna is generally required in order to track such EM signals. Frequency independent antennas such as spirals and quasi-frequency independent antennas such as log-periodic antennas are quite large and their use in an antenna array is quite limited. Also, an adaptive array using such broadband elements would require a feed structure integrated to a true-time delay network in order to achieve multiple beams and beam scanning. Such feed networks are difficult to design and are expensive to implement.
Therefore, there exists a need in the art for an adaptive wideband antenna capable of dynamic reconfiguration of operating frequency, polarization, bandwidth, number of beams and their spatial directions, and radiation pattern shape without the need for a feed network.
The disadvantages associated with the prior art are overcome by a reconfigurable adaptive wideband antenna capable of dynamic reconfigurability of several antenna parameters. Specifically, the present invention is a reflect array antenna comprising a reconfigurable conductive substrate and a single broadband feed. The reconfigurable conductive substrate is capable of dynamically forming conductive surfaces that can be used as reflective elements in the array. The conductive surfaces are electronically painted on the substrate using plasma injection of carriers in high-resistivity semiconductors. The reflective elements can be configured in many formations, including frequency independent fractal formations, that allow for wideband operation of the antenna.